There are various systems of cattle production around the world. In some countries, the cattle production is dual-purpose, with cows being used to provide milk and meat. However, for the most countries, cattle production may be divided into two sectors: (1) dairy production and (2) meat production (Acker &Â Cunningham 1991). In continental Europe and the developing countries, the same cattle are used as a source of both meat and milk. In contrast, in the countries of the developed world such as the UK, Australia, New Zealand, the USA, and Canada meat production and milk production have been separated (Ball & Peters, 2004).
In the UK, the proportion of herds with more than 100 cows is increasing rapidly (Ball & Peters, 2004). The whole milk pricing system, which historically based on the percentage of butterfat, tends to change as more people are drinking low-fat and skim milk (Acker &Â Cunningham 1991) but still butterfat has been appreciated as the most valuable content of whole milk. The economy for dairy farmers has been also changed with declining milk prices and higher cost for feed. This is the main reason behind the continuous trend of fewer numbers of dairy farmers in the country, and increasing numbers of cows per farm, which means that the farmer spends less time per cow (Ball & Peters, 2004). In the UK, the population of the cattle decreased after the BSE epidemic and the subsequent outbreak of foot-and mouth disease. Those cows that remain need to reproduce even more efficiently to provide a good choice of replacement stock, adapted in the new market trend for products with lower content of fat (in meat and in milk).